The present invention relates generally to the suppression of fires in electrical boxes and more particularly to the use of an intumescent material to suppress fires within an electrical box.
It is well known that electrical fires are one of the most common sources of fires in the home and elsewhere. In the home, electrical fires may occur within electrical boxes, which may house either electrical devices or electrical connections such as cable splices. A typical electrical box consists of a box made of metal or plastic which may be rectangular or round and which has an open face for access to the inside of the box. Openings are provided in the sides or back of the box for insertion of electrical cables. An electrical device such as a light switch or outlet plug is mounted within the box, and the box is often installed in an opening in a wall. A plastic or metal cover plate is then attached to the electrical device to cover the electrical box and to provide a pleasing outward appearance.
Fires within electrical boxes present particular hazards for the home or other buildings in which they occur. Electrical boxes which contain switches or outlet plugs are typically housed within the walls of the building. If a fire starts in the electrical box, it may spread to the surrounding wood frame and quickly travel throughout the inside wood framing of the structure. Electrical fires also can be hard to detect because they begin within an enclosed electrical box. Thus, they may be well underway before emitting smoke. Further, electrical devices are often placed within the vicinity of plastic or synthetic materials, and thus such fires can produce toxic or hazardous fumes and smoke.
Currently, there are no systems which adequately suppress fires which begin in an electrical box. It has been known generally to use intumescent materials to protect and insulate items from a fire. Intumescent materials are products that "grow" or "thicken" when exposed to heat, creating an insulated layer that separates the protected item from the fire. Conventionally, intumescent materials are applied to the exterior of an item to insulate it from a fire. For example, intumescent materials have been used to create a fire-resistant/retardant wrap suitable for protecting the exterior of conduits and cable trays and the like from a fire. Such a system is described in Kiser, U.S. Pat. No. 5,681,640. In addition, intumescent materials have been applied to large sheets of insulated material for use as an exterior wrap which may be applied to the exterior of a building. However, the exterior application of such intumescent materials, while protecting the material or structure surrounded by such intumescent materials from fire, does not actively suppress fires that begin within an enclosed area, or protect against fires which begin in an enclosed area such as an electrical box.
Accordingly, there is still a need for a system that suppresses fires that begin within an electrical box, that insulates the exterior plate from a fire within an electrical box, that prevents smoke from exiting from an electrical box fire, that is easy to install, and that is cost-effective.